The Proposed International Unit of Candle Power

Abstract

j-(c The i\Torl<i~ig Btaudnids of Tight and their U s e in the Pliotoiiietry of CiiLq," Cli. 0. Boi13, V r d d i i i Iii>t. l!KM. 1 1:i.f. cit.

The standardisation of light and photometry – A historical review

“…The national laboratories agreed to equate their national standards to a new unit, the 'International Candle', given in Table 2. [52][53][54][55]60 The Pentane, Carcel and Hefner standards required essentially no adjustment, but Figure 6 Violle platinum incandescent light standard (simplified). 39 The flame heater C is above the mobile platinum crucible C', with water-cooled viewing aperture at D' for optical path mirror M America needed a 1.6% reduction of its electric standard candle to finally bring about this unification of standards.…”

“…The national laboratories agreed to equate their national standards to a new unit, the ‘International Candle’, given in Table 2. 52–55,60…”

“…29,52 However the value they determined for the Hefner lamp was low at 0.88 of a British Candle and standardised in a set of incandescent lamps. [53][54][55] This resulted in an significant difference between the two American standards.…”

“…57 The concept was energetically promoted by Violle (Walsh 47 lists 32 of his publications from 1881 to 1905) and accepted by the International Electrical Congress in 1889, with 1/20 part of the Violle emission being termed the 'Bougie de´cimale', representing 1.04 of the existing Carcel standard. 39,55 However, this incandescent standard proved to be even less reproducible than the flame standards, the sole successful Carcel comparison being done by Violle himself. 55 The presence of even a slight amount of foreign material on the surface or impurity of the platinum greatly affected the amount of light emitted.…”

“…39,55 However, this incandescent standard proved to be even less reproducible than the flame standards, the sole successful Carcel comparison being done by Violle himself. 55 The presence of even a slight amount of foreign material on the surface or impurity of the platinum greatly affected the amount of light emitted. 47 It was further discovered in 1914 that platinum emissivity in the red wavelengths drops 15% on freezing, which helped explain many of the inconsistent results.…”